Differences between Working stress method and Limit state method

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Design of RCC Structures

The design of the components of the RCC structure can be done in the following two ways:

  1. Working Stress Method
  2. Limit State Method
Methods of RCC Design
Methods of RCC Design

Here are some of the design procedures of the components of the RCC structures:

Design of RCC beams

Design of RCC columns

Design of RCC staircase

Design of Foundations

Design of Simply Supported Slabs

In this article, we are going to discuss the major difference between the two important methods of RCC design. This will help us understand the mechanics of the Structural Design and which method is to be adopted for better efficiency.

Working Stress Method

  • The Stresses in an element is obtained from the working loads and compared with permissible stresses.
  • The method follows linear stress-strain behaviour of both the materials.
  • Modular ratio can be used to determine allowable stresses.
  • Material capabilities are under estimated to large extent. Factor of safety are used in working stress method.
  • The member is considered as working stress.
  • Ultimate load carrying capacity cannot be predicted accurately.
  • The main drawback of this method is that it results in an uneconomical section.

Limit State Method

  • The stresses are obtained from design loads and compared with design strength.
  • In this method, it follows linear strain relationship but not linear stress relationship (one of the major difference between the two methods of design).
  • The ultimate stresses of materials itself are used as allowable stresses.
  • The material capabilities are not under estimated as much as they are in working stress method. Partial safety factors are used in limit state method.

25 thoughts on “Differences between Working stress method and Limit state method”

  1. i dinesh kumar amhto working for civil engineer construction line .we want working methodes Rcc work. column and beam I not geting actual design for black coton soil footing , Black coton soil depth is max 1.5 to 2.meter.

  8. Iam working for civil engineer construction line .we want working methodes Rcc rectangular under ground tanks Pumping Stations and Circulars Pumping stations with column and beam I not geting actual design

  13. sbc of the soil is defined as the intentisty of load which can bear on its per unit volume without failure.
    (soil failure is the movement of soil from its actual place)

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